It is argued that an understanding of the attentional processes which influence the selection of "effective" stimuli from the vast array of "available" stimuli is important for theories of person perception. Research is proposed which applies to person perception attentional concepts and data which have been generated in research on object and speech perception. Five determinants of attentional allocation will be investigated: arousal, set, sex, and weight of the perceiver, and the discriminability of available stimuli. The effects of these variables on attentional span, lability, and selection will be ascertained from several indices of attention in person perception. These will include causal attributions for a stimulus person's behavior, recall of the behavior, and cognitive and emotional reactions to various cues which have been associated with the stimulus person's behavior.